Don't sweat it! Remember to play for the fun of it. If you get hung up on winning, you won't enjoy chess much. Only strive for slow improvements. I've improved from about a 1200 rating to about 1700 over the past two years or so. I still occasionally lose against a player rated like 1300 though, and tactics puzzles often baffle me. Playing tactics puzzles will help you spot forks and pins, combinations and such, but you'll make the most improvement by playing game after game.
When practicing tactics, try to practice one type of situation over and over. A knight fork for instance. Do that till you get bored, then move to opening traps or something like that. Just don't try to do everything all at once.
Hope this helps.
I am a lifelong chessplayer with no regular play or methodical study. This week I started playing the chess tactics here, on the Chess Tactics Server, and in Chessmaster, but although most of the time I can eventually see the solution, it takes me a long time sometimes to see it. If I do this regularly, will this change? It is frustrating the c*#@p out of me.